The heart of a computer is a magnetic hard disk drive (HDD) which typically includes a rotating magnetic disk, a slider that has read and write heads, a suspension arm above the rotating disk and an actuator arm that swings the suspension arm to place the read and/or write heads over selected circular tracks on the rotating disk. The suspension arm biases the slider into contact with the surface of the disk when the disk is not rotating but, when the disk rotates, air is swirled by the rotating disk adjacent an air bearing surface (ABS) of the slider causing the slider to ride on an air bearing a slight distance from the surface of the rotating disk. When the slider rides on the air bearing the write and read heads are employed for writing and reading magnetic transitions corresponding to the host data. The read and write heads are connected to signal processing circuitry that operates according to a computer program to implement the writing and reading functions.
The volume of information processing in the information age is increasing rapidly. In particular, it is desired that HDDs be able to store more information in their limited area and volume. A technical approach to this desire is to increase the capacity by increasing the recording density of the HDD. To achieve higher recording density, further miniaturization of recording bits is effective, which in turn typically requires the design of smaller and smaller components.
The further miniaturization of the various components, however, presents its own set of challenges and obstacles. Particularly, attempts to increase achievable recording density of storage systems have also caused conventional products to experience an undesirable increase in noise when reading data stored therein.
Moreover, improvements to magnetic recording involve increasing reader resolution in the down-track and cross-track directions. However, reader resolution and SNR are strongly determined by reader sensitivity which has been the source of most improvements previously achieved in conventional products, but is now reaching the achievable limits thereby barring further advancement.
Additionally, conventional products have attempted to increase data read rates, e.g., to shorten data access time. However, such attempts have ultimately required spinning the HDD at higher revolutions per minute, thereby increasing power consumption and error rates while reading the data stored thereon.
It follows that conventional products have fallen short of developing viable improvements to the SNR. In sharp contrast, various embodiment described herein include data storage systems and methods that achieve improved SNR, as will be discussed in detail below.